چكيده به لاتين
Adhesive joints are widely used in various industries due to their advantages and ease of application compared to other joining methods. This research focuses on enhancing the electrical conductivity and mechanical properties of epoxy adhesives by incorporating Graphene nanoplatelets (G), iron oxide nanofillers (Fe3O4), and a hybrid nanofiller (Hy) consisting of an equal weight percentage mixture of G and Fe3O4. Single lap adhesive specimens containing these nanofillers at weight percentages of 2%, 3%, and 4% were fabricated and tested under tensile load at different temperatures: room temperature, 45°C, and 88°C. The results reveal that the addition of G, Hy, and Fe3O4 nanofillers enhances shear strength and electrical conductivity at both room and elevated temperatures without altering the epoxy's glass transition temperature (Tg). The tensile tests showed that the influence of nanofillers on the shear strength of adhesive joints varies depending on the type, weight percentage of the added nanofillers, and the testing temperature. For Graphene, the incorporation of 2 wt%, 3 wt%, and 4 wt% at 88°C led to increases in shear strength of 112.2%, 112.6%, and 82.5%, respectively. A similar trend was observed for Fe3O4 nanofillers, where additions of 2 wt%, 3 wt%, and 4 wt% at 88°C resulted in enhancements in adhesive joint strength by 50%, 60.8%, and 25.3%, respectively. For the hybrid nanofiller, the incorporation of 2 wt%, 3 wt%, and 4 wt% at 88°C led to shear strength improvements of 95.4%, 98.3%, and 56.9%, respectively. Regarding electrical conductivity under varying load ratios (F/Fmax) and temperatures (25°C, 45°C, 88°C), the testing of neat epoxy revealed that at a 60% load ratio, the conductivity was 7.91 × 10-14 S/mm at 88°C. After adding the nanofillers, electrical conductivity improved significantly. The best electrical conductivity for Fe3O4 was 0.00495 S/mm at 25°C with a 4 wt% addition without load. The hybrid nanofiller (Hy) also showed improved electrical conductivity, outperforming Graphene with a conductivity of 0.000442 S/mm at 45°C with a 4 wt% addition without load. For G, the conductivity was 6.85506 × 10-5 S/mm at 45°C without load. Scanning Electron Microscopy (SEM) revealed that at 2 wt%, no noticeable agglomerations were present; however, agglomerations began to form at 3 wt% and were clearly visible at 4 wt% for both G and Fe3O4. In contrast, the hybrid (Hy) showed no signs of agglomeration, indicating that mixing G with Fe3O4 reduces agglomerations. Overall, G and the hybrid (Hy) demonstrate superior performance in improving shear strength compared to Fe3O4, with the optimal weight percentage identified as 3 wt% for G and Fe3O4; higher percentages led to decreased shear stress due to agglomeration. Conversely, Fe3O4 and the hybrid (Hy) exhibit superior performance in improving electrical conductivity compared to G. This study provides valuable insights into optimizing epoxy adhesives for enhanced electrical conductivity and mechanical performance under varying temperature conditions.
